Various types of telecommunication systems are available to provide services for satisfying particular needs. For example, private automatic branch exchange (PABX) switching systems are available for servicing businesses having a few subscriber sets up to thousands of subscriber sets. Typically, PABX systems are readily adapted for use with small businesses, and wherein a switchboard attendant typically receives incoming calls and controls the switching system to provide the calling party a telecommunication path through the PABX system to the called party.
Key telephone systems are another type of switching system which are generally less sophisticated for economically serving a relatively few number of telephone sets. The basic key telephone system includes a number of key telephone sets connected through a central control unit to each of a number of key telephone sets. Each key telephone set includes a number of subscriber lines connected thereto. Thus, when an incoming call is directed to such a system, a lamp is lit on each telephone set to indicate an incoming call. The button associated with the ringing line can be pushed on any telephone set so that any party can respond to the incoming call and inquire as to the identity of the desired called party. The party initially answering the key telephone set then communicates, either verbally or by way of intercom or public address broadcast facilities, the identity of the called party and the line number associated with the incoming call.
More sophisticated key telephone systems provide the same general function, but include additional features such as the ability to place a line on hold, paging, intercom, music-on-hold and access to centralized dictating equipment.
While key telephone systems continue to be improved, such as by the addition of new features and functions, processor controlling the system to enhance its flexibility, carrying out functions with electrical or integrated circuits which were heretofore conducted by mechanical elements, etc., the basic shortcoming of such systems is that the first party to answer the incoming call must function somewhat as a switchboard attendant, in that such person must control the system and direct the incoming call to the appropriate called party. Hence, the completion of a call employing a key telephone set generally requires the cooperation of two persons. Not only is this an uneconomical use of time, but also the calling party has to communicate generally with an intermediate person before a final connection is made to the desired called party.
From the foregoing, it can be seen that a need exists for telecommunication facilities adapted for streamlining a key telephone system, and enabling more efficient completion of telephone calls to called parties associated with such a system. An associated need exists for call processing equipment which is readily adapted to function in conjunction with a key telephone system, without substantial modification to such system.